China says that 80 cracks have appeared in the Three
Gorges dam, only days after the huge reservoir behind it was filled for
the first time.

"If water enters these cracks, there could be negative
effects, so we are fixing them very carefully," Pan Jiazhong, head
of the dam's inspection group, said yesterday.

He denied that the cracks threatened the dam's safety,
but said they could expand and cause leaking unless repaired.

The reservoir now extends upstream for 219km (350 miles),
with a maximum water depth of 135 metres (440ft).

A failure of the dam could have catastrophic consequences
downstream in the fertile and densely populated middle Yangtze valley.

Another official said the project had already displaced
more than 700,000 people: a higher figure than previous estimates.

Guo Shuyan, director of the construction committee, said
that dozens of towns had been evacuated and 13 larger urban communities
rebuilt on higher land.

He admitted that there was insufficient land for the
farmers who have been moved.

"We're now studying how to make improvements in
their living standards," he said.

Measures were being considered to protect the dam against
an attack by terrorists, he added.

Cracks in the upstream face of the dam were first revealed
in March last year by Chinese journalists.

Dam engineers at the Three Gorges project development
corporation said this was a "normal phenomenon" but added that
the faults would be remedied.

Last month Mr Pan made a more detailed statement about
the cracks, saying that experts were "particularly concerned".

It was reported only on the Yangtze river commission
website, while national publicity focused on the "successful"
filling of the reservoir.

Mr Pan said then that it was "too early to be proud"
of the dam. "We have a long way to go ... I hope we will do our best
to build a first-class project rather than a dam with 10-metre long cracks!"

The final inspection showed that some of the vertical
cracks on the dam that had been repaired had reopened, "even though
we put a great deal of money and effort into the repair work".

He said the dam would face its first real test in the
severe floods expected this summer.

"Of course we ought to be well prepared for powerful,
disastrous floods," he said.

"Please, let us never lower our guard in this respect."

Earlier he told the Three Gorges project inspectors that
the 39bn cubic metres of water stored in the reservoir would be the"real
examiners" of its success.

Floods, earthquakes and landslides would "show no
mercy" if mistakes were made.

The project, the biggest of its kind in the world, is
designed to provide electricity to central China and to diminish the risk
of floods.

The second stage of filling the reservoir, due to be
completed in 2009, will take the depth to 175 metres and extend the lake
to the city of Chongqing.

At least 600,000 more people will have to be moved from
settlements along the river banks .

Critics acknowledge that cracks are not unknown in newly
built big dams, but they fear that corners may have been cut in order to
achieve the arbitrary deadlines laid down by Beijing for political reasons.

A huge operation to remove such sources of pollution
as industrial waste water, toxic wastes and disused public toilets from
the reservoir bed before it was filled has fallen behind schedule.

Last month the state environmental protection administration
issued a directive calling on officials to redouble their efforts to remove
all possible sources of infectious disease.